The goal of this proposal is to study the regulation of hemoglobin synthesis in normal and abnormal human erythroid cells. The Beta thalassemias and related disorders provide a series of mutations in the Gamma-Delta-beta gene complex which permit analysis of the relationship between changes in gene structure and altered gene function. In these disorders, there is decreased or absent Beta globin synthesis. The clinical and biochemical heterogeneity of these diseases suggest that they are due to many different defects. Recent advances in recombinant DNA technology and gene transfer techniques provide the technical framework for investigating these disorders. The specific aims of this grant are: (1) to more precisely define the different types of gene defects in Beta+ and Beta thalassemia and related disorders by cloning of the genes involved and their direct nucleotide sequencing; (2) to use gene expression systems to determine the changes in function caused by the altered structure of these genes. Cloned human globin genes will be introduced into mammalian cells through vectors containing viral components which permit the replication and expression of these genes; and (3) to create specific globin gene mutations by in vitro mutagenesis which will permit additional analysis of the effect of changes in structure on function. These studies should characterize the DNA in this group of human disorders and determine their effect on globin gene transcription, globin mRNA processing, and globin mRNA metabolism. These experiments may provide new insights into the mechanisms controlling globin gene expression, and could lead to new approaches to the therapy of these severe anemias.